Noise eliminator



g- 1932- E. B. STIMPSON 1,870,428

NOISE ELIMINATOR' Filed May 27. 1927 Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE EDWIN B. STIMPSON, F BROOKLYN, NEVT YORK, ASSIGNOR TO EDWIN B. STIMPSON COMPANY, OF BROOKLYN, NEW YORK NOISE ELIMINATOR Application filed May 27, 1927. Serial No. 194,627.

This invention relates to a noise eliminating device for moving parts of machinery, especially for pedal-operated devices such as riveting machines.

In such machines it is customary to use a spring to return the parts to starting position after each operation, and the return stroke is accompanied by considerable shock and noise.

The present invention eliminates these undesirable results by providing a pneumatic check for slowing down and cushioning the return stroke.

WVhile preferred forms of the invention 35 have been disclosed for purposes of illustration, it should be understood that various changes may be made in the structure without departing from the spirit and scope of the invention as hereinafter set forth and claimed.

In the drawing;

Fig. 1 is a side elevation of a machine cmbodying the invention;

Fig. 2 is a fragmentary vertical section through the noise eliminator;

Fig. 3 is a section on line 33 of Fig. 2 but showing a difierent form of valve.

Referring to the drawing more particularly the reference numeral 10 has been applied to the upright pedestal of the machine, while numeral 11 refers to the head which has a curved forward extension 12. An operating lever 13 is pivoted at 14 to the extension 12 and has an operating connection at 15 with the vertical plunger 16 which is guided in its reciprocating movement by a plate 17 bolted to the front of extension 12. An arm 18 projects forwardly from the head 11 and carries an anvil 19 directly below, and cooperating with, plunger 16.

A foot lever 20 is pivoted at 21 to the pedestal 10 and projects forward to a point accessible to the operator. A lever 22 is pivotally connected to the operating lever 12 at 23 and to the foot lever at 24, the levers 20 and 22 constituting toggle mechanism for moving the lever 13. The foot lever is returned to normal starting position by a tension spring 25 which has one end attached to the pedestal at 26 and its opposite end secured at 27 to the forward arm of the foot if lever.

The noise eliminating device comprises a vertical cylindricalbore 28 formed in the rear part of the head 11. A plunger 29 slides in the bore with an air-tight fit. The lower end of the bore is reduced as at 30, forming a conical shoulder 31 upon which the ball valve 32 is adapted to seat. The small bore 30 extends through the frame to communicate with the atmosphere at the port 33, which forms an inlet by which air gains access to the cushioning cylinder. A threaded aperture 34 passes through one side of head 11 and connects with the bore 28. The screw 35, which seats in aperture 34, has a longitudinal passage 36 which forms an opening for the slow escape of air from the cylinder.

The upper end of the plunger 29 is connected to the lever 13 in any suitable manner,

the embodiment illustrated having a link 37 hinged at one end to the plunger and connected at the opposite end to the joint 23.

The device operates in the following manner:

When the operator depresses the treadle the toggle levers raise the rear end of lever 13, causing the plunger 16 to move clownwardly to perform the operation for which it is designed. At the same time the plunger 29 moves upwardly, unseating valve 32 and drawing air into the cylinder. Upon releasing the treadle it is pulled upwardly by the spring 25, which movement causes the plunger 29 to descend, closing valve 32 and trapping air in the cylinder. The passage 36 allows the air to escape slowly from the cylinder, thereby retarding the return stroke of the operating parts. After the plunger passes the aperture 34 the air no longer can escape, but is compressed, forming a pneumatic cushion which absorbs the rest of the force of the return stroke, and eases the parts down to starting position. By locating the aperture 34 at the proper distance above the lowest point of piston travel it is possible to cushion the return stroke in such a way that the stops 38 carried by the head 11 and lever 13 will make contact with 100 out appreciable shock or noise.

Any suitable check valve can be used to o control the passage leading into the bottom of the cylinder, one possible variation in the form of a cone valve being illustrated in Fig. 3. It will also be clear that the noise eliminator can be used on any machine in which it is found desirable to cushionth'e contact of relatively moving parts.

I claim v A dash pot operative to permit unre strained operating motion of a machine, but to pneumatically restrain the return motion until it is nearly completed and then pneumatically cushion it; said dash pot comprising an air cylinder open at one end and closed at the" other by a conical valve seat leading to an inlet opening, a check valve seated wholly by gravity and operable to admit air to the closed end of the cylinder, a removable plug providing an air leak in the cylinder wall spaced from the closed end of the cylinder, and a piston within the cylinder, the piston having a length exceeding the distance between the air leak and the final position of the piston end on the return stroke, the side wall of said piston comprising a cut-off valve for the air leak when the piston is'in final position.

In testimony whereof ture.

I afiix my signa- EDWIN B. STIMPSON. 

